What is the difference between programing on the layout using Track A and B and using a dedicated programing track using Pgm A & B.
Is there a difference in voltage, packets, protocol between the two?
Broadcast programming, also called service mode programming, uses a programming track.
The programming track is electrically separate from the rest of the railroad, and is connected to the "PROG A" and "PROG B" terminals of your DCS100/200 or Zephyr (Xtra) command station.
One major advantage to a programming track is that many systems can read-back the Configuration Variables (CV's) that are in the mobile decoder.
Digitrax has several command stations that are able to read-back these values.
The outputs of the PROG A and PROG B terminals normally have no voltage present and cannot run trains; when actually programming, there are flashes of voltage up to around 12 Volts.
Digitrax decoders commonly use a service mode programming called Paged Mode Programming.
There are other forms of broadcast programming, such as physical register mode and direct mode; neither are commonly used with Digitrax systems and Digitrax decoders.
Operations Mode Programming
Ops Mode, also called Programming on the Main by some, allows for the programming of mobile decoders while they are on an operating layout.
For example, this method is useful for speed matching locomotives in an MU set (multiple units operating from one master address).
There are also some decoders that can only be programming in Ops Mode.
While it is possible to create mayhem when using Ops Mode, it is unlikely since each decoder must be specifically addressed to be programmed.
Most Digitrax decoders have ops mode programming capability and all current Digitrax command stations can send ops mode programming commands.
The DT40x series throttle can perform Ops Mode programming, while the UT4 series utility throttle cannot.
Many decoders do not allow changes to CV01, the 2 digit address or CVs 17 & 18, the 4 digit address.
In these cases, changes of the address must be made with service mode programming on a programming track.
In operation, because Ops Mode is being done on an active railroad, the voltages will be normal Track A and Track B voltages, depending upon the scale.